Lumen Terms of Service

We grant you a personal, non-exclusive, revocable licence to install and use Lumen on devices you own or control, for your own studying. You may not resell the app, redistribute modified builds as if they were ours, or use our name, logo, or branding to imply endorsement.

Lumen's source code is published under the MIT Licence. Where the MIT Licence grants you broader rights over that source code, it governs the code; these terms govern your use of the app we distribute through the app stores and the branding that accompanies it.

You keep all rights to the decks, notes, cards, images, and recordings you create or import. We claim no ownership over them and, because they stay on your device, we receive no licence to them at all.

You are responsible for what you import. Do not import material you have no right to use: shared Anki decks and other files may be covered by copyright or licence terms of their own, and honoring those is your responsibility, not ours.

Lumen stores your data locally and does not sync it to any server of ours. That means uninstalling the app, resetting its data, losing the device, or a device or filesystem failure can destroy your study history permanently, and we cannot recover it for you.

Use the export feature to keep your own backups. You accept that keeping backups is your responsibility.

Do not use Lumen to break the law, to infringe anyone's rights, or to store material you are not permitted to hold. Do not attempt to interfere with the app's operation, and do not use the URL import feature to attack, overload, or gain unauthorized access to any server.

Lumen schedules reviews using the FSRS-6 algorithm, which estimates when you are likely to forget something. It is a model, not a promise. We do not guarantee any particular learning outcome, retention rate, exam result, or level of language proficiency. Editing the scheduling parameters changes how the algorithm behaves, and the results of doing so are on you.

Lumen can import files you point it at and can open external links. We do not control, endorse, or verify third-party content, files, or servers, and we are not responsible for them. The bundled HSK vocabulary is derived from a publicly available dataset and is provided as a study aid without any warranty of accuracy.

We may update, change, or discontinue Lumen or any of its features. We may stop distributing it or supporting older versions. We will not intentionally break your locally stored data in an update, but we do not promise indefinite availability of the app or of any specific feature.

Lumen is provided "as is" and "as available", without warranties of any kind, whether express or implied, including any implied warranties of merchantability, fitness for a particular purpose, or non-infringement. We do not warrant that the app will be uninterrupted, error-free, or free of data loss.

To the fullest extent permitted by law, MTS Studio is not liable for any indirect, incidental, special, consequential, or punitive damages, or for any loss of data, study history, profits, or goodwill, arising out of your use of Lumen. Where liability cannot be excluded, it is limited to the greater of the amount you paid us for the app in the twelve months before the claim, or ten United States dollars.

Some jurisdictions do not allow certain exclusions or limitations, so parts of this section may not apply to you. Nothing here limits liability that cannot lawfully be limited, including for fraud or for death or personal injury caused by negligence.

You may stop using Lumen at any time by uninstalling it. We may terminate this licence if you materially breach these terms. The disclaimers and liability limits above survive termination.

These terms are governed by the laws of the Republic of Indonesia, without regard to conflict-of-laws rules. Disputes will be brought before the competent courts of Indonesia, except where your local consumer-protection law gives you the right to bring a claim where you live.

We may revise these terms. The effective date above shows the current version, and material changes will be noted in the app's release notes. Continuing to use Lumen after a revision means you accept it.

MTS Studio, Indonesia. Questions about these terms: [email protected].